Drill guide with angle verification

Abstract

A method and instrument is used for inserting a bone screw through a hole in a bone plate into bone at a maximum angulation of a bone screw central longitudinal axis with respect to a central axis of the hole. The maximum angulation places the head of the bone screw at or below an outwardly facing surface of the bone plate. The instrument has a distal end including a gauge element spaced proximally from an end surface of the distal end when in contact with a counterbore surrounding the plate hole a distance less than a depth of the counterbore. The instrument is tilted with respect to a central axis of the bone plate hole to an angle wherein the gauge element remains at or below the outwardly facing surface of the bone plate adjacent the counterbore. A hole is drilled through a guide bore in the instrument.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]The present application is a divisional of U.S. patent application Ser. No. 12 / 317,703, filed on Dec. 23, 2008, the disclosure of which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The invention relates to an angle guide for orienting a bone screw in a bone plate. More particularly, the invention relates to an instrument for insuring the position of the head of a bone screw located within a bone plate hole.[0003]It is often necessary when utilizing bone plates either for fracture fixation or such as tibial base plates to couple the bone plates to bone via a screw extending through a hole in the plate. When the screw is angled, surgeons have had to eye the correct angle specified by the device manufacturer indicated by the surgical situation. If the bone screw is put in at too great an angle the bone screw head would sit proud of the bone plate which in some situations is undesirable. The surgeon would then either co...

AI Technical Summary

Benefits of technology

The patent describes a device used in orthopedic surgery that helps a surgeon determine the correct angle for drilling pilot holes in a device used for bone fixation. The device has visual indicators like lines or colors that help the surgeon ensure the correct angle for the bone screw. This ensures that the device and the implant are properly aligned, allowing the screw to be securely seated in the bone. Overall, this device improves the accuracy of drilling pilot holes and enhances the overall surgery's success.

Problems solved by technology

If the bone screw is put in at too great an angle the bone screw head would sit proud of the bone plate which in some situations is undesirable.

The surgeon often had difficulty eyeing the correct angle especially where there was a plurality of bone screws to be inserted, since the correct angle is relatively small i.e. zero to ten degrees.

Normally, the surgeon drills a pilot hole in the bone prior to inserting the bone screw and it has been difficult to drill the pilot hole at the correct angle so that the bone screw would seat properly.

Consequently, if the pilot hole and subsequent bone screw are inserted at an incorrect angle the head of the bone screw could impinge on the distal surface of the polyethylene bearing implant which is undesirable.

Such an impingement could lead to metal or polyethylene debris which has been known to cause osteolysis.

However, since most bone screws include cutting flutes at the leading ends thereof continued rotation of the cutting flutes causes the bone to degrade and allows more play in the screws positioning.

While this may allow the bone screw to seat properly, it reduces the compressive forces holding the plate to the bone by decreasing the holding ability of the screw.

This method may not always be successfully since the drill and screw will have a tendency to follow the original drilled hole.

Even if the surgeon is capable of resetting the new desired angle, there is still damage to the bone in the originally drilled area which may cause fracture propagation.

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